D3.js is a JavaScript library for manipulating documents based on data. D3 helps you bring data to life using HTML, SVG and CSS. D3’s emphasis on web standards gives you the full capabilities of modern browsers without tying yourself to a proprietary framework, combining powerful visualization components and a data-driven approach to DOM manipulation.
Download the latest version here: d3.v3.zip

In interactive visualisation, there is the word reactive. Well, maybe not literally, but close enough.
The fact is that reactivity, or the propension of a visualisation to respond to user actions, can really help engage the user in a visualisation, and help them understand its results. Both of which are usually good things. How can this reactivity be achieved? Through animations.
So I’ll go ahead and state that animation, if done right, can make any interactive data visualization better.
How is that?